If he was 16 or older, that would be legal where I'm from. The teacher would be fired for exploitation of power, but that would be about it. I wonder how old he is...
I can't at some of you. Blaming the girl for being 'pressedT' and 'no fun' when she literally just found out not only did her boyfriend cheat on her but it was with a 38-year-old man. Get a grip out of your teacher/student/daddy/taboo fantasies
The only bad thing about this whole situation is that this guy was his teacher. But unless he forced himself onto the younger guy, I don't see what's so bad about this.